Conventionally, under arbitrary processing, when a series of data (transaction) is transmitted from a transmission source device to a transmission destination device, the transaction is divided into packets and transmitted (refer to Japanese Laid-Open Patent Publication No. 2005-519530). If there are multiple transactions, packets belonging to each transaction are transmitted in a specified sequence. For example, for given transactions A and B, the specified sequence may be an alternating transmission of 1 packet of transaction A and 1 packet of transaction B.
There are occasions when packets are transmitted in a sequence that differs from the specified sequence. In the example of transactions A and B, a differing sequence may be the skipping of a packet of transaction A and successive transmission of packets of transaction B. In a similar way, conversely, a packet of transaction B may be skipped and packets of transaction A may be successively transmitted.
Causes of packet skipping include errors that occur when the operation of the transmission source device is faulty (first cause) and occasions determined by communication protocol, design specifications related to the transmission source device, etc. (second cause). Communication protocol is a set of standard rules related to communication over a network. Although verification engineers are interested in verifying only the first cause, for packets transmitted by a transmission source device, the first and the second causes exist.
Accordingly, after understanding communication protocol and design specifications and determining whether the cause of a skip is the first cause or the second cause, a verification engineer verifies the transmission source device for a packet skipped as a consequence of the first cause. Nonetheless, a problem arises in that if the communication protocol, design specifications, etc. are complicated, the user may misjudge the cause of the skip.